On Saturday we arrived back in Kangerlussuaq after spending a week camping near the edge of the Greenland Ice Sheet. We spent our time learning about each other’s science and working together on field projects. One of the objectives of Dartmouth’s IGERT in Polar Environmental Change is to “have an interdisciplinary view of polar regions and their importance to global environmental change.” To fulfill this requirement we’ve taken classes to strengthen our interdisciplinary science backgrounds, but seeing and experiencing the science first hand in the field is sometimes the most instructive.
At the beginning of our trip we came up with the idea of an “interdisciplinary index” to rank how involved or curious we were about each other’s science. At first we tried coming up with a 1 to 10 scale to rate our “I” index, but quickly realized that the scale was too subjective. Instead we decided that indicating whether our “I” index was increasing or decreasing would be most effective. For example, if an aquatic ecologist (Lauren) was walking to explore a pond by herself while the rest of the group looked on, the “I” index would decrease. Conversely, if an aquatic ecologist (Lauren) started walking to a pond to explore and was joined by a curious engineer (Kaitlin) and an ecosystem ecologist (Julia), the “I” index would sky-rocket. And we’ve had some great high “I” index days.
One of our higher “I” index moments was when we extracted a sediment core from a lake in front of the Greenland Ice Sheet. Lake sediments, much like ice cores, are great archives of past climate changes. I use lake sediment cores in my research to determine a glacier’s history. Sediments, plants, insects and other organic matter that are washed into the lake can give clues about the past environment. We can study the sediments to determine their source. Or was it a time when a lot of vegetation was growing in the lake or being washed into it? Are there any plant fragments in the core that we could use to radiocarbon date the sediment layers? Maybe we would find some insect or plant fossils that would tell us about the environment at the time of deposition? The possibilities are almost endless.
In order to find out, we extruded the sediment core in the field. Usually we would do this step in the lab, but we decided that if our preliminary core showed promising results, we would return to the lake with the intention to extract a longer core. We were all excited by what we found when we extruded the core. The sediments in the top half were of glacial origin – silts, clays and sands. The bottom half of the core contained silt and high amounts of organic matter, indicating that the depositional environment was very different. This is when the “I” index really started to climb. Lauren (who studies aquatic insects) was interested in the insects that may have been preserved in the sediments; Chris (who studies sea ice) speculated on how the small pebbles found in the lake sediments may have originated as ice rafted debris; Simone (who studies plants) was curious about the tiny plants fragments we could see in the mud. All of these fantastic observations helped piece together the past climate puzzle and made for a stratospherically high “I” index!